The present invention relates to an automatic focusing camera.
With the conventional automatic focusing cameras with an ultrasonic or optical distance measuring device, in response to a reading of the distance to object, a photographic lens is shifted to a focusing position by a spring and ratchet mechanism or by a servomotor and then a shutter is released. Therefore they are complex in construction and control devices are very expensive.
In the automatic focusing cameras of the type using the spring and ratchet mechanism, the spring is used to shift the photographic lens and the ratchet mechanism is used to stop the lens at a focusing position. In addition, a power source for driving the ratchet mechanism and a power supply control circuit for controlling the power supply to the ratchet mechanism are needed. As a result, the constructions are very complex. In addition, it is very difficult to attain the correct timing for causing the ratchet mechanism to arrest the lens, thereby stopping it at a focusing position. Furthermore, the component parts must be fabricated within extremely accurate dimensional tolerances. Moreover due to the wear of mutually engaging parts of the lens and ratchet mechanism, the lens cannot be stopped at a correct focusing position.
With the automatic focusing cameras of the type using a servomotor for shifting the lens, the servomotors themselves are very expensive and highly advanced technologies are required to design and construct the circuits for controlling the servomotor. As a result, it becomes difficult to supply at inexpensive costs the automatic focusing cameras for general users.